Adjustable radius rule



Dec.l3,1949 j E. J.IPETREIY I 2,491,330

ADJUSTABLE RADIUS RULE 2 Sheets-Sheet 1 Filed Jan. 3, 1946 Inventor Edmund J Peire @M II B WW /E Dec. 13, 1949 E. J. PETRE ADJUSTABLE RADIUS-RULE 2 Sheets-Shet 2 Filed Jan. 5, 1946 will m mg V va N2 I rweutor Edmond elpell' e Patented Dec. 13., 1949 UNITED STATES PATENT OFFICE 2,491,330 ADJUSTABLE RADIUS RULE Edmond J. Petre, Armonk, N. Y.

Application January 3, 1946, Serial No. 638,745

4 Claims.

This invention relates to improvements in devices for making circles having various radii.

An object of the invention is to provide an adjustable radius rule, which may be set to automatically flex or bend an indicating blade to the desired curvature of a circle having a radius equal to the setting on the rule.

Another objectoi the invention is to provide an improved adjustable radius rule used for drafting and other purposes, which will instantly indicate the curvature of a circle having any pre-selected radius.

A further object of the invention is to provide an adjustable radius rule which will be highly efiicient in use and relatively inexpensive to manufacture and produce.

Other objects will appear as the description proceeds.

In the accompanying drawings part of this application,

Figure 1 is a front elevation of the improved adjustable radius rule;

Figure 2 is an edge View of the adjustable radius rule;

Figure 3 is a transverse sectional view through the rule with portions thereof being removed;

Figure 4 is an enlarged front elevation partly broken away and with portions thereof removed;

Figure 5 is an enlarged detail view of the hinge connection between the flexible blade and a pair of connecting spokes;

Figure 6 is a sectional view taken on the line 65 of Figure 4, and

Figure 7 is a sectional view taken on the line 1-1 of Figure 1.

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

In carrying out the invention, there is provided a body member I formed with the oppositely-disposed laterally extending spaced finger-shaped extensions 2 and. 3, through which the arcuate slots 4 and 5 of varying length are respectively formed.

Disposed on the opposite sides of the body I, are the cooperating pairs of arms 5 and I, which are pivoted on the body I, on the pivot pins or bolts 8' and 9. The arms 5 and 'I are provided with arcuate slots l and II, respectively, of varying length.

The blade supporting members I2 and it are secured by rivets M or otherwise to the opposite sides of the body I at the base thereof, and support the slotted flexible steel blade I which has which form a a point or line contact only with the said body I, as shown in Figure 3 of the drawings.

Suitable spaced bearing ears IS are secured to the inner surface of the blade I5 at spaced points along its length, four sets of bearing ears being illustrated at either side of the center of the blade. Pivot pins I! will extend through the ears I6 and will support the outer ends of the pairs of spokes I8, whose inner ends are mounted on the ends of pivot pins I9 extending through the slots I0 and II in the pairs of arms 6 and I, and also through the slots 4 and 5 in the body I. The spokes are positioned to extend on the outer sides of the said arms 5 and I.

The outermost pairs of spokes 29 and 2i are pivoted at 22 and 23 to the arms 6 and I, as clearly illustrated in Figure 1 of the drawings.

A handle member 24 comprising spaced elements 25 and 26, is secured to the top of the body I by means of the rivets 21 and extends upwardly therefrom. Slots 28 and 29 are formed in the elements 25 and 26 respectively, and the sides of the front element 25 is provided with suitable indicia or calibrations 36 to indicate fractions of inches.

Slide members 3E and 32 are positioned between the elements 25 and 26, and are provided with the laterally extending ears 33 and 35, respectively. An indicator 35 is supported by the slide member 3 I, and extends transversely of and in front of the calibrations 30 on the element 25.

Yokes 38 and 31 are secured by pins 38 and 39 to the ears 33 and 34, and support the spokes 40 and 4| whose outer ends are connected by the pins 42 and 43 to the outer ends of the arms 6 and I.

The support 44 is positioned at the outer end of the handle member 24 and extends outwardly therefrom on either side, the same distance as the edges of the blade I5, so that the rule will lie evenly on the work on which the circles are being drawn.

Locking set screws 45 and 46 will extend through the slot 29 in the rear element 26 and into the slide members 3| and 32, to lock the same in the desired adjusted position.

From the foregoing description, it is believed the mode of operation of the adjustable radius rule will be readily understood.

When it is desired to draw a circle having a specified radius, it is only necessaryto set the indicator on the proper calibration on the handle member 29 and lock the indicator in place. Moving the slides will automatically move the arms 6 and I simultaneously or separately with respect to the body I, which movement will be transmitted through the various blocks and spokes to the blade [5. It will be understood that either slide may be adjusted to secure a desired curvature on the blade end l5, so that one end of the blade may be set for a circle having one radius, while the other end of the blade may be set for a circle having a difierent radius. Also, if both ends of the blade are set for the same setting on the handle; member, the whole blade will be fle-xed': to the curvature of 21. circle having a .singleradiua While the preferred embodiment of the invention has been disclosed in the drawings and specie fication, it will be understood that it is notiine tended to be limited by this disclosure, as many minor changes in detail of construction may-be resorted to without departure from the spirit of the invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United Statesis:

1. An adjustable radius rule including abody having similarly formed sets of slots formed through its opposite, sides, a flexible blade, secur-ed centrally of its length to one endofsaid body intermediate the sets of slots, a longitudinally slotted calibrated rule fixed to the diametrically. opposite end of saidbody and extending outwardly therefrom,,a pair of similarly formed slotted arms pivotally attached to the, opposite sidesof said body with their slots intersecting the slots in said body, spokes pivotally secured at their outer ends to said flexible blade, pivot pins connected with the inner ends of saidspokes extending through the intersection of said slots in said body and arms, spokes pivotally attached between the outer ends of said arms andsaid flexible blade, adjustable slides mounted in the slot in said rule, and means connected between said slides and the extreme outer ends of'said slotted arms, whereby curvature adjustment of each half of said flexible blade may be accomplished by varying the position or one or the other of said slides intheslotted rule.

2.- An adjustableradius rule including a body having similarly formed sets of slots formed through its opposite sides, a flexible longitudinally slotted bladesecuredcentrally of its length to-one end of said body intermediate the sets of slots, a longitudinally slotted calibrated rule fixed tothe diametrically opposite end of said body and extending outwardly therefrom, a pair of similarly formed slotted arms pivotally attached tothe opposite sides of said body with their slots intersecting the slots in saidbody, spokes pivotally secured at their outer ends to said flexible blade, pivot pins connected with the inner ends of said spokes extending through the intersection of slots in said body and arms, spokes pivotally attached between the outer ends of said arms and said flexible blade, adjustable slides mounted in the slot in said rule, locking means supported by said slides, spokes connected between said slides and the extreme outer ends of said slotted arms, whereby radius of; curvaturev adjustment of ,each h alf, of said flexible blade, may be accomplished by varying the position of one or the other of said slides in the slotted rule.

3. An adjustable radius rule including a body having similarly formed sets of slots formed through itsopposite sides, a longitudinally slotted flexible blade engageable with one end of said body intermediate-the sets of slots, a longitudinallyslotted calibrated rule fixed to the diametrically opposite end of said body and extending outwardly therefrom, atpair of similarly formed slotted arms pivotally attached to the opposite sides of said body with their slots intersecting the slots in said body, spokes pivotally secured at their outer ends to said flexible blade, pivot pins connected with the inner ends of said spokes extending through the intersection of said slots in said body and arms, spokes pivotally attached between the outer ends of said arms and said.

flexible blade, adjustable slides mounted in the slot in said rule, locking means supported by,

said slides, spokes connected between said slides and the extreme outerends of saidslotted arms, whereby radius'orcurvature adjustment of said flexible blade may beselectively accomplished by varying the position of one or the other of said slidesin the slotted rule.

4. The subject matter as claimed in claim 3,

and a work-engaging support on the outer end of said slotted rule;

EDMOND J. PETRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

